Amines are commercially produced on a broad scale by various processes. For example, an amine, such as ethylenediamine, may be commercially produced by the reaction of ethylene dichloride and an excess of anhydrous ammonia vapors under pressure at a temperature of 150.degree. C. Anhydrous needles of ethylenediamine hydrochloride and other higher diamines are obtained. This product is treated with caustic soda to yield the free amine which is recovered from the diamine vapors, steam and unreacted ammonia by a dehydrating column where the diamine is dried and condensed.
In another procedure, ethylene dichloride is treated with excess aqueous ammonia in a pressurized reaction chamber at 110.degree. C. and 10-200 atmospheres of pressure. The mixture of reaction products containing ethylenediamine hydrochloride, ammonium chloride and ammonia in aqueous solution is heated with aqueous caustic soda and fractionated. The ethylenediamine is drawn off and the ammonia released from the ammonium chloride is returned to the reactor.
Both of the above-described processes result in metal chloride as a reaction by-product. The chloride is obtained in impure form with a mixture of alkylene-amines as the principal contaminants. The mixture of amines includes low-molecular weight amines (ethylenediamine mol. wt. 60) to high-molecular weight amines (piperazines, polyamines etc. mol. wt. &gt;200). This indicates that the heavier amines may be trapped within the crystal lattice of the metal chloride crystals and could not be removed by water while the low-molecular weight amines that have a greater affinity for water would migrate into water as they would tend to be on the outside surfaces of the metal chloride crystals.
It is desirable to recover the amines from the metal chloride by-product as the recovery of these products will improve the overall productivity of the process. In addition, it is also desirable to avoid contaminating natural waterways with amines when by-product metal chloride from amine synthesis reactions is discharged.
It has now been found that a properly sequenced combination washing and treatment process will separate the amines from salt so that the separated amines will be economically recoverable and the effluent will have a sufficiently decreased amine content that will not adversely affect the environment. The disclosed process has been found to be up to 98% effective in separating amines from metal chloride.
Accordingly, it is a principal object of this invention to provide an improved process for the separation of amines from the amine-containing soluble metal chloride by-product of an amine synthesis reaction.
It is also an object of this invention to provide a novel process of separating amines from the metal chloride by-product of an amine synthesis in such an efficient manner that the amines may be economically recovered.
It is also an object of this invention to provide a novel process for separating amines from the metal chloride by-product of an amine synthesis so that the amine content of the metal chloride by-product will be sufficiently reduced so that the environment will not be adversely affected by disposal into natural waterways.